This invention relates to apparatus for controlling the flow of a large volume of high pressure, high temperature fluid such as a gas. Particularly, it relates to a valve structure which is fast acting and capable of precise control to provide selected flow rate profiles. More particularly, the invention relates to a valve structure of the afore-described type which utilizes a multiplicity of few distinct components, is easily assembled and maintained, and may be readily controlled with a high degree of precision.
Valve structures of the type disclosed herein have particular utility in wind tunnel applications wherein the shock wave formation of an explosion is replicated. The valve structure should be capable of controlling fluid flow to provide a fast response, instantaneous maximum flow rate representing an initial shock wave and to provide a controlled closing to represent trailing shock waves. Wind tunnels for conducting tests utilizing replicated shock waves are necessarily large to accommodate apparatus to be tested. Therefore, the volume of fluid to be controlled is large and consequently, the valve structure itself is large. In order to achieve the desired magnitude of shock wave, it is contemplated that the wind tunnel be supplied with high pressure, high temperature fluid from plural, parallel sources and that multiple valve structures of the type disclosed herein be provided, one for each fluid supply. Generally, large size and multiplicity contravene fast operation and precision control.
U.S. Pat. No. 3,875,964 issued Apr. 8, 1975 to Harry Friedland discloses a valve structure of the type to which this invention is related. This patent discloses valve elements bolted directly to flanges on a plurality of pipes permanently embedded in a concrete bulkhead. The pipes and the corresponding valve element are of three sizes, the largest being many times the size of the smallest. This size differential impacts the operational speed of the various valve elements, the larger valves operating slower than the smaller valves, and makes precision timing in the control more difficult. The movable slide of the valve element is external to the valve body, and therefore subjected to the high pressure in the system being controlled. Closure of the valves occurs under spring pressure when an actuating force is removed.